The precursor-guided hydrothermal synthesis of CuBi2O4/WO3 heterostructure with enhanced photoactivity under simulated solar light irradiation and mechanism insight.

Z-scheme heterojunction can efficiently suppress the electron-holes recombination and promote the charges transfer rate, which result in the high photocatalytic performance. Herein, a flower-flake-sphere like CuBi2O4/WO3 hybrid photocatalyst was fabricated via a precursor-guided hydrothermal method. The morphology, structure, composition, chemical and electronic properties of the as-prepared samples were systematically investigated by multiple techniques (XRD, FT-IR, SEM, TEM, XPS, UV-vis, BET, PL, ESR. etc.). Particularly, the 60 wt% CuBi2O4/WO3 nanocomposite exhibited the highest photocatalytic activity for tetracycline (20 mg/L) degradation under simulated solar light irradiation. The rate constant was 0.0179 min-1, which was almost 8 times and 4.5 times higher than that of bulk WO3 and CuBi2O4, respectively. The experimental results confirmed that CuBi2O4 made a direct Z-scheme heterojunction by band alignment with WO3, which are conducive to the efficient charges separation and prolonged carriers lifetime. According to the quenching experiments, •OH and •O2- were testified to be the predominant active species. The electrons accumulated in the CuBi2O4 negative CB and the holes in the WO3 positive VB made significant contribution to the strong redox ability of the CuBi2O4/WO3 nanocomposite. This work provides some deep insights into the design of band-alignment-based Z-scheme heterostuctures, which is also applicable to other catalytic system.